#include <d3d8.h>
//一個指向DIRECT3D8對象的指針
LPDIRECT3D8 g_pD3D = NULL;
//一個指向DIRECT3DDEVICE8設備對象的指針
LPDIRECT3DDEVICE8 g_pD3DDevice = NULL; 
// Buffer to hold vertices
//聲明一個用于保存頂點的緩沖區
LPDIRECT3DVERTEXBUFFER8 g_pVertexBuffer = NULL;


struct CUSTOMVERTEX
{
	// The transformed position for the vertex.
	// 頂點坐標的變換
    FLOAT x, y, z, rhw;		
    // The vertex colour.
	//頂點顏色
	DWORD colour;			
	
};

#define D3DFVF_CUSTOMVERTEX (D3DFVF_XYZRHW|D3DFVF_DIFFUSE)

#define SafeRelease(pObject) if(pObject != NULL) {pObject->Release(); pObject=NULL;}

//初始化D3D對象
HRESULT InitialiseD3D(HWND hWnd)
{
    //First of all, create the main D3D object. If it is created successfully we 
    //should get a pointer to an IDirect3D8 interface.
    //構造一個D3D對象
	g_pD3D = Direct3DCreate8(D3D_SDK_VERSION);
    if(g_pD3D == NULL)
    {
        return E_FAIL;
    }

    //Get the current display mode
	//得到現實模式
    D3DDISPLAYMODE d3ddm;
    if(FAILED(g_pD3D->GetAdapterDisplayMode(D3DADAPTER_DEFAULT, &d3ddm)))
    {
        return E_FAIL;
    }

    //Create a structure to hold the settings for our device
	//申明一個D3DPRESENT_PARAMETERS結構體用來保存當前顯示設備設置
    D3DPRESENT_PARAMETERS d3dpp; 
    ZeroMemory(&d3dpp, sizeof(d3dpp));

    //Fill the structure. 
    //We want our program to be windowed, and set the back buffer to a format
    //that matches our current display mode
	//填充結構體，用于顯示當前顯示模式模式
	//窗體模式
    d3dpp.Windowed = TRUE;
	//
    d3dpp.SwapEffect = D3DSWAPEFFECT_COPY_VSYNC;
    d3dpp.BackBufferFormat = d3ddm.Format;

    //Create a Direct3D device.
	//創建設備對象
    if(FAILED(g_pD3D->CreateDevice( D3DADAPTER_DEFAULT, 
								    D3DDEVTYPE_HAL, 
									hWnd, 
                                    D3DCREATE_SOFTWARE_VERTEXPROCESSING, 
									&d3dpp, 
									&g_pD3DDevice)))
    {
        return E_FAIL;
    }
    
    return S_OK;
}

//初始化頂點緩沖區
HRESULT InitialiseVertexBuffer()
{
	VOID* pVertices;
	//保存三角形各個頂點以及它們的顏色
	//Store each point of the triangle together with it's colour
	CUSTOMVERTEX cvVertices[] =
	{
		{250.0f, 100.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(255, 0, 0),},	//Vertex 1 - Red	(250, 100)
		{400.0f, 350.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(0, 255, 0),},	//Vertex 2 - Green	(400, 350)
		{100.0f, 350.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(0, 0, 255),},	//Vertex 3 - Blue	(100, 350)
        {400.0f, 100.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(255, 0, 0),},
		{400.0f, 350.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(0, 255, 0),},
		{100.0f, 350.0f, 0.5f, 1.0f, D3DCOLOR_XRGB(0, 0, 255),},
	};
     //從設備創建頂點緩沖
	//Create the vertex buffer from our device
	if(FAILED(g_pD3DDevice->CreateVertexBuffer(6 * sizeof(CUSTOMVERTEX),//
                                               0, D3DFVF_CUSTOMVERTEX,
                                               D3DPOOL_DEFAULT, &g_pVertexBuffer)))
	{
		return E_FAIL;
	}

	//得到指向頂點緩沖的指針并鎖定頂點緩沖
	//Get a pointer to the vertex buffer vertices and lock the vertex buffer
	if(FAILED(g_pVertexBuffer->Lock(0, sizeof(cvVertices), (BYTE**)&pVertices, 0)))
	{
		return E_FAIL;
	}
    //拷貝保存在cvVertices中的值到頂點緩沖中
	//Copy our stored vertices values into the vertex buffer
	memcpy(pVertices, cvVertices, sizeof(cvVertices));
    //解除頂點緩沖的鎖定
	//Unlock the vertex buffer
	g_pVertexBuffer->Unlock();

    return S_OK;
}

void Render()
{
    if(g_pD3DDevice == NULL)
    {
        return;
    }
    //清空背景緩沖為黑色
    //Clear the backbuffer to black
    g_pD3DDevice->Clear( 0, 
						 NULL, 
						 D3DCLEAR_TARGET, 
						 D3DCOLOR_XRGB(0, 0, 0), 
						 1.0f, 
						 0
						);
    
    //Begin the scene
	//開始場景渲染
    g_pD3DDevice->BeginScene();
    
     //渲染三角形
    //Rendering our triangle
	//邦定頂點緩沖到設備數據流中
	g_pD3DDevice->SetStreamSource( 0,  //指定數據流，范圍從0-Streams-1 
								   g_pVertexBuffer,  //指向IDirect3DVertexBuffer8接口返回對象的指針，描述所綁定到的數據流對象
								   sizeof(CUSTOMVERTEX));//頂點緩沖大小
	//設置頂點陰影模式
	g_pD3DDevice->SetVertexShader(D3DFVF_CUSTOMVERTEX);
	//頂點緩存渲染頂點
	g_pD3DDevice->DrawPrimitive( D3DPT_TRIANGLELIST,
							     0, 
								 2
								);


    //End the scene
    g_pD3DDevice->EndScene();
    //將后緩沖設置到前緩沖
    //Filp the back and front buffers so that whatever has been rendered on the back buffer
    //will now be visible on screen (front buffer).
    g_pD3DDevice->Present(NULL, NULL, NULL, NULL);
}

void CleanUp()
{
	SafeRelease(g_pVertexBuffer);
	SafeRelease(g_pD3DDevice);
	SafeRelease(g_pD3D);
}

void GameLoop()
{
    //Enter the game loop
	//開始游戲循環
    MSG msg; 
    BOOL fMessage;

    PeekMessage( &msg, 
				 NULL, 
				 0U, 
				 0U, 
				 PM_NOREMOVE);
    
    while(msg.message != WM_QUIT)
    {
        fMessage = PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE);

        if(fMessage)
        {
            //Process message
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
        else
        {
            //No message to process, so render the current scene
            Render();
        }

    }
}

//The windows message handler
//windows消息處理函數
LRESULT WINAPI WinProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
        case WM_DESTROY:
			//系統的退出消息
            PostQuitMessage(0);
            return 0;
        break;
        case WM_KEYUP: 
            switch (wParam)
            { 
                case VK_ESCAPE:
                    //User has pressed the escape key, so quit
					//當按下escape鍵時銷毀hWnd指向的窗體
                    DestroyWindow(hWnd);
                    return 0;
                break;
            } 
        break;

    }
          //默認的系統消息處理函數
    return DefWindowProc(hWnd, msg, wParam, lParam);
}

//Application entry point
INT WINAPI WinMain(HINSTANCE hInst, HINSTANCE, LPSTR, INT)
{
      //Register the window class
	//用于注冊windows窗體類的設置
    WNDCLASSEX wc = {sizeof(WNDCLASSEX), CS_CLASSDC, WinProc, 0L, 0L, 
                     GetModuleHandle(NULL), NULL, NULL, NULL, NULL,
                     "DX Project 2", NULL};
    RegisterClassEx(&wc);

  	
	//Set the mouse pointer to an arrow
	//設置鼠標指針
    HWND hWnd = CreateWindow("DX Project 2", "www.andypike.com: Tutorial 2", 
                              WS_OVERLAPPEDWINDOW, 50, 50, 500, 500,
                              GetDesktopWindow(), NULL, wc.hInstance, NULL);

	//Initialize Direct3D
	//初始化Direct3D對象
    if(SUCCEEDED(InitialiseD3D(hWnd)))
    { 
        //Show our window
		//顯示窗體
        ShowWindow(hWnd, SW_SHOWDEFAULT);
        UpdateWindow(hWnd);

		//刷新窗體顯示
		if(SUCCEEDED(InitialiseVertexBuffer()))
		{
		//Start game running: Enter the game loop
		//進入游戲循環
			GameLoop();
		}
    }
    
    //清理資源
    CleanUp();
    //取消窗體類注冊
    UnregisterClass("DX Project 2", wc.hInstance);
    
    return 0;
}